柳杉與相思樹木焦油作為木材防腐劑之潛力

Potential of Wood Tars from Cryptomeria japonica and Acacia confusa as Wood Preservatives

黃識頻(Shih-Pin Huang)

指導教授 ： 顏才博

國立屏東科技大學/國際學院/熱帶農業暨國際合作系/碩士(2013年)

https://doi.org/10.6346/NPUST.2013.00034

摘要

本研究目的為研發以柳杉 (Cryptomeria japonica) 與相思樹 (Acacia confusa) 經炭化熱裂解製得之木焦油為基礎之低毒性木材防腐劑，以提升國產造林木之應用價值。國產柳杉與相思樹木材經炭化熱裂解後製得木焦油，再以不同極性之有機溶劑進行液相-液相分配，得到正己烷(n-Hexane)可溶部、乙酸乙酯(Ethyl acetate)可溶部及水可溶部。木焦油與其各可溶部分別以固態平板培養基法及土壤木塊試驗法，評估其抑菌效果。所使用之五種木材腐朽菌菌種分別為：白腐菌(Lenzites betulina及Trametes versicolor)，褐腐菌(Laetiporus sulphureus，Fomitopsis pinicola及Gloeophyllum trabeum)；木塊耐腐朽性評估係依照中華民國國家標準之CNS 6717標準法及美國材料試驗協會(ASTM D1413-07)標準法進行試 驗；處理材藥劑流失與保留之評估，則將試材經14天淋溶試驗後，計算其藥劑留存率及藥劑流失率。此外，木材之尺寸安定性評估，則將試材置於27°C與90%相對溼度恆溫恆濕箱中32天，測量處理材之尺寸變化。結果顯示兩種木焦油於1750 μg/mL時對L. betulina之抑制率最高，對於其他菌種之抑菌效果，皆隨濃度降低而明顯降低。進一步評估二種木焦油各可溶部之抗菌活性得知，正己烷可溶部的抗菌活性較乙酸乙酯可溶部佳。木塊耐腐朽試驗結果得知，4.0%濃度柳杉、相思樹木焦油處理之柳杉試材經G. trabeum與L. sulphureus褐腐菌腐朽後，其重量損失率分別僅為2.89% / 3.40%與3.26% / 2.98%；然而二種木焦油之正己烷可溶部之整體抑菌效果均優於其乙酸乙酯可溶部，證實木材分別經二種木焦油及其正己烷可溶部含浸處理後能有效地減少木材腐朽菌之危害。淋溶試驗結果顯示，柳杉、相思樹木焦油及其正己烷可溶部之藥劑留存率，則隨著藥劑濃度之增加而提升；其藥劑流失率，皆隨著藥劑濃度之增加而減少。此外，根據柳杉、相思樹木焦油及其正己烷與乙酸乙酯可溶部處理材尺寸安定性之評估結果得知，其平衡含水率(equilibrium moisture content)與體積膨脹率(volumetric swelling)，皆明顯地低於對照組，同時亦證明二種木焦油及其正己烷可溶部能有效地改善試材之尺寸安定性。綜合上述結果顯示，柳杉、相思樹木焦油之正己烷可溶部，除具有良好的抗淋溶性，同時可有效地提升處理才之耐腐朽性與尺寸安定性，具有進一步研發為低毒性木材防腐劑之潛力。

關鍵字

柳杉 ； 相思樹 ； 木焦油 ； 木材防腐劑 ； 木塊耐腐朽性 ； 淋溶性 ； 尺寸安定性

並列摘要

Increasing the value and efficacy of utilization for the tree species in Taiwan’s forest is an important issue in the development of sustainable forest management. Therefore, the objective of this study is to investigate the potential of wood tars, obtained respectively from Cryptomeria japonica and Acacia confusa, as wood preservatives to increase their utilization and value. Wood tars were produced by carbonization of pyrolysis from the woods of C. japonica and A. confusa, and their different soluble fractions (n-Hexane, Ethyl acetate, and water) were partitioned by liquid-liquid chromatography. In this study, two white-rot fungi (Lenzites betulina and Trametes versicolor) and three brown-rot fungi (Laetiporus sulphureus, Fomitopsis pinicola, and Gloeophyllum trabeum) were used in the anti-fungal agar assay and soil-block decay test. Anti-fungal activity was carried out by agar plate assay, and wood decay resistance was evaluated by the soil-block decay test according to the Chinese National Standard (CNS 6717) and the American Society for Testing and Materials standard (ASTM D1413-07). Leachability was assessed on treated woods by measuring their chemical retention and chemical loss percentages after a 14 day leaching test. Dimensional stability was analyzed by the change of equilibrium moisture content and volumetric swelling in a 27°C and 90% relative humidity chamber for 32 days. Results of the anti-fungal agar assay indicated that both wood tars exhibited high inhibition against L. betulina at 1750 μg/mL. The results of anti-fungal activities for soluble fractions showed that n-Hexane soluble fractions of C. japonica and A. confusa performed better than those of Ethyl acetate soluble fractions on all wood decay fungi, while all water soluble fractions revealed no anti-fungal effect. Furthermore, results of the soil-block decay test indicated that wood (C. japonica) treated with 4.0% C. japonica and A. confusa wood tars inhibited G. trabeum growth with only 2.89% and 3.40% weight loss, respectively, while the weight loss of its control group was 35.89%. Similarly, woods treated with 4.0% C. japonica and A. confusa wood tars revealed respective weight loss of 3.26% and 2.98% against L. sulphureus, which were lower than its control group (32.38%). Moreover, a concentration dependency was observed between weight loss and treatment; the higher the concentration of the treatment, the lower the weight loss percentage of the treated wood. The leaching test results showed that the chemical retention of wood treated with C. japonica, and A. confusa wood tars, and their n-Hexane fractions increased as the concentration increased. On the other hand, a decrease in the chemical loss of treated wood was observed as the concentration increased. According to the dimensional stability test, the significant decrease of equilibrium moisture content (EMC) and volumetric swelling (VS) indicated that C. japonica, and A. confusa wood tars, and their n-Hexane acetate soluble fractions could increase the dimensional stability of treated wood. As a result, wood tars of C. japonica and A. confusa, as well as their n-Hexane soluble fraction, demonstrated excellent performance on wood decay resistance, leachability and dimensional stability, suggesting great potential to be developed as wood preservatives in the future.

並列關鍵字

Cryptomeria japonica ； Acacia confusa ； wood tar ； wood preservatives ； soil-block decay test ； leachability ； dimensional stability

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